Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Persistent slab avalanches remain a low-likelihood, high-consequence concern on upper elevation north aspects. Pockets of reactive windslab may be found just below ridgelines and along the edges of gullies. Small wet loose avalanches are possible today on middle and lower-elevation sun-warmed aspects.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–3

    Skiers and riders could trigger persistent slab avalanches up to 5 feet deep on northerly aspects at upper elevations. Triggering one is unlikely but not impossible. This is a low-likelihood, high-consequence scenario. 

    In the central and northern Bitterroot, weak basal facets near the ground are the primary layer of concern. In the southern Bitterroot, it is a crust/facet layer just above the rain crust.

    Choosing slopes under 35º and avoiding trigger points like convex rolls and thin spots around rocks and windswept ridges is the best way to manage this problem. 

    Dig before stepping into steeper terrain. If you find soft sugary snow under a stiffer slab, step back to mellower slopes. These layers will likely not give a warning before failing, and their presence can only be ascertained by looking in the snowpack.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Winds have been light and predominantly westerly for the past 48 hours, there has been little snow transport, and warm temperatures are helping wind slab bond. However, pockets of reactive windslab may remain just below ridgeline and along the edges of gullies. While mostly small, these are large enough to carry skiers and riders into hazards such as terrain traps. Check for red flags, such as shooting cracks on representative slopes before committing to slopes over 35º, and avoid skiing on wind loaded pockets.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    If the sun makes a long enough appearance, small wet loose avalanches are possible on middle and low-elevation slopes in the Bitterroot today. These pose little risk to skiers and riders unless they are encountered on steep slopes over terrain traps. If rollerballs are starting, it's an indication that the snow is warming, and wet loose avalanches are possible. 

Avalanche Discussion

It’s been a mild week for weather, just a trace of new snow, light winds, and mild temperatures. As a result, there isn’t much new to report on avalanche stability.

The hazard is improving and trending lower. However, facets on upper elevation north slopes keep it at moderate. There is still too much uncertainty about the layer to remove it from the problems. Poor structure can still be found, weak sugary snow sits under a cohesive slab, and stability tests point to the possibility of triggering a slide. This is a low likelihood/high consequence problem. There is lots of good riding at other aspects and elevations, and given the destructive potential of this problem, it’s best to give it more time to bond.

Where there is a supportive crust from the Christmas rain, there is little likelihood of triggering a slide. However, where the crust is thin, a possibility of triggering a slide on weak layers remains. Remember, low danger doesn’t mean no danger. 

Continue to practice safe travel. Assess the snowpack, stay alert for Red Flags, ski and ride one at a time, and stop in safe zones. If in doubt about the stability, step back to slopes less than 35º.

Please submit an observation, even if it's to tell us that the stability and skiing were good. That’s valuable information.

Ski and ride safe.

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